System and method for detecting radio frequency signals and controlling vehicle operations in response thereto

ABSTRACT

In at least one embodiment, a system for determining the location of a wireless device with respect to a vehicle is provided. The system comprises a plurality of antennas positioned about the vehicle for receiving a radio frequency (RF) signal from the wireless device. The RF signal corresponds to at least one of a command and status related to a predetermined vehicle operation. The system further comprises a controller operably coupled to each antenna. The controller is configured to generate a location signal indicative of the location of the wireless device based on the arrival time of the RF signal at one or more antennas of the plurality of antennas and to control the operation of the predetermined vehicle operation based on the location signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/236,043 filed Sep. 23, 2008, the disclosure of which is incorporatedin its entirety by reference herein.

TECHNICAL FIELD

One or more embodiments of the present invention described hereingenerally relate to a system and method for detecting radio frequency(RF) signals and controlling vehicle operations in response thereto.

BACKGROUND

Tire pressure monitoring systems, remote keyless entry systems, passiveentry/passive start, and or immobilizer systems for automotiveapplications are known to include one or more antennas positioned aboutthe vehicle to receive radio frequency signals from RF basedtransmitters. Such transmitters may be in the form of tire pressuresensors that transmit tire pressure information to one or more of theantennas. The antennas, in turn, present the RF signal to a receiver ina controller. The controller processes such signals to determine momentsin which one or more of the tires include a low tire pressure reading.The controller generally determines the location of the tire thatincludes a particular tire pressure sensor based on ID informationcontained within the RF signal.

The keyfob may be used in conjunction with a passive entry/passive startsystem. With passive entry, the controller generally determines whichdoor to unlock based on the location of the keyfob with respect to thevehicle. With passive start, the controller determines whether thedriver is in the vehicle based on the location of the keyfob. Forexample, the controller may be able to determine whether the keyfob isin the vehicle within the driver's zone.

A number of RF based vehicle operations (including those stated above)offered in vehicles today generally utilize multiple discrete antennasthat are distributed throughout the vehicle to identify the location ofthe RF transmitter with respect to the vehicle. Along with such discreteantennas, elaborate wiring and tuning is generally needed to identifythe location of the RF transmitter with respect to the vehicle.

SUMMARY

In at least one embodiment, a system for determining the location of awireless device with respect to a vehicle is provided. The systemcomprises a plurality of antennas positioned about the vehicle forreceiving a radio frequency (RF) signal from the wireless device. The RFsignal corresponds to at least one of a command and status related to apredetermined vehicle operation. The system further comprises acontroller operably coupled to each antenna. The controller isconfigured to generate a location signal indicative of the location ofthe wireless device based on the arrival time of the RF signal at one ormore antennas of the plurality of antennas; and to control the operationof the predetermined vehicle operation based on the location signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is pointed out with particularity in the appendedclaims. However, other features of the present invention will becomemore apparent and the present invention will be best understood byreferring to the following detailed description in conjunction with theaccompany drawings in which:

FIG. 1 depicts a system for detecting radio signals in a vehicle inaccordance to one embodiment of the present invention;

FIG. 2 depicts a first detailed diagram of the central controller inaccordance to one embodiment of the present invention;

FIG. 3 depicts RF bursts received on the multiple channels in accordanceto one embodiment of the present invention;

FIG. 4 depicts an RF burst signal waveform and chirp modulation;

FIG. 5 depicts a zone map used to determine the direction of a receivedRF signal in accordance to one embodiment of the present invention;

FIGS. 6A and 6B depict tables in accordance to one embodiment of thepresent invention;

FIG. 7 depicts a hyperbolic grid used to determine the location of thewireless device within a zone of the zone map in accordance to oneembodiment of the present invention; and

FIG. 8 depicts a method for determining the location of the wirelessdevice with respect to the vehicle in accordance to one embodiment ofthe present invention.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousand alternative forms. The figures are not necessarily to scale; somefeatures may be exaggerated or minimized to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the present invention.

The embodiments of the present invention as set forth in FIGS. 1-7generally illustrate and/or describe at least one controller (ormodule), or other such electrically based components. All references tothe various controllers and electrically based components and thefunctionality provided for each, are not intended to be limited toencompassing only what is illustrated and described herein. Whileparticular labels may be assigned to the various controllers and/orelectrical components disclosed, such labels are not intended to limitthe scope of operation for the controllers and/or the electricalcomponents. The controllers (or modules) may be combined with each otherand/or separated in any manner based on the particular type ofelectrical architecture that is desired or intended to be implemented inthe vehicle.

Referring now to FIG. 1, a system 10 for detecting radio signals in avehicle 12 in accordance to one embodiment of the present invention isshown. The system 10 includes a wireless device(s) 14 and an antennaarray 16. The wireless device 14 may be implemented as one of a keyfob,cell phone, one or more tire pressure sensors, or other suitabledistributed transponder generally recognized to facilitate transmissionof RF based signals to the vehicle 12

The antenna array 16 generally comprises a plurality of antennas 16 a-16n positioned within a headliner of the vehicle 12. Each antenna 16 a-16n may be omni-directional such that RF signals may be received from anydirection. The antennas 16 a-16 n may also be bi-directional or othersuitable configuration. A central controller 18 is operably coupled tothe antennas 16 a-16 n for receiving RF signals therefrom. The headlinermay provide a non-conducting structure which extends close to each ofthe windows of the vehicle 12 for RF visibility. It is generallyunderstood that the antenna array 16 may be positioned anywhere in thevehicle. Further, the antennas 16 a-16 n may separated such that one ormore of the antennas are positioned in the headliner of the vehicle andthe remaining antennas are positioned in other areas of the vehicle. Theparticular arrangement of the antennas 16 a-16 n in the vehicle may varybased on the desired criteria of a particular implementation. It isgenerally contemplated that the length for each antenna 16 a-16 n withrespect to the central controller 18 be similar to one another. In yetanother example, the antennas 16 a-16 n may be positioned within thecentral controller 18 provided the RF signal is comprised of a highfrequency (e.g., 10 GHz or above).

Each antenna 16 a-16 n includes at least one channel that is differentfrom one another. For example, antenna 16 a includes channel CHAN_A,antenna 16 b includes channel CHAN_B, antenna 16 c includes channelCHAN_C, and antenna 16 n includes CHAN_N for receiving one or more RFsignals from the wireless device 14 on another channel. In general, atleast one channel (e.g., CHAN_A-CHAN_N) may be configured to transmit RFdata back to the wireless device 14.

Each antenna 16 a-16 n may be coupled to a flat flexible transmissionline or coaxial cable that is fed to the central controller 18. A bodycontroller 20 (or other suitable vehicle controller) may be operablycoupled to the central controller 18 for receiving commands and othersuch data therefrom. In one example, a data bus may be used tofacilitate communication between the central controller 18 and the bodycontroller 20. The data bus may be a Control Area Network (CAN), LocalInterconnect Network (LIN), or other such suitable data communicationlink generally recognized to facilitate data communication betweencontrollers in a vehicle. In another example, the body controller 20 mayalso include an antenna (not shown) to facilitate communication with thecentral controller 18 for wireless communication.

The system 10 may be implemented to perform vehicle operationscomprising of, and not limited to, remote keyless entry (RKE),carfinder, passive entry, passive start, immobilizer, TPMS, wirelessswitching (e.g., commands generated from wireless devices on doors forcontrolling unlock/lock, open/close window or other such operationperformed by a switch on the door), and/or wireless occupancy detectionin response to RF signals transmitted from the wireless device(s) 14.The central controller 18 may transmit RF signals to the wireless device14 in the event a particular vehicle operation such as passiveentry/start or car finder is executed.

In general, the central controller 18 is configured to determine thedirection and/or location of the wireless device(s) 14 with respect tothe vehicle 12 such that any vehicle operation that desires the locationof the wireless device may operate for its intended purpose. The centralcontroller 18 may generate a location signal that is indicative of thelocation of the wireless device 14 with respect to the vehicle. Thecentral controller 18 transmits the location signal to the bodycontroller 20 in response to receiving RF signals from the wirelessdevices 14. As noted above, the TPMS vehicle operation generallyrequires knowledge of the whereabouts of each tire pressure sensor sothat the body controller 20 identifies the particular tire that isexperiencing the low pressure condition in response to theidentification signal. For passive entry/start function, the bodycontroller 20 may identify which door to unlock and confirm that the key(or wireless device 14) is in the vehicle to perform the passiveentry/start function, respectively in response to the identificationsignal. For immobilization function, the body controller 20 may identifywhether the key (or wireless device 14) is out of the vehicle toimmobilize the vehicle (e.g., prevent the vehicle from starting) inresponse to the identification signal. The body controller 20 maylock/unlock a particular door or open/close a particular window inresponse to the central controller 18 determining which switch (orwireless device 14) on a particular door is transmitting a command. Inaddition, the body controller 20 may determine which seat is occupied byan occupant in response to the central controller 18 receiving signalsfrom wireless sensors (or wireless devices 14) positioned in variousseats of the vehicle 12. All of the above, are non-limiting examples inwhich it may be necessary to determine the location of the particularwireless device 14 that is transmitting RF signals with respect to thevehicle 12.

Referring now to FIG. 2, a detailed diagram of a portion of the centralcontroller 18 in accordance to one embodiment of the present inventionis shown. The central controller 18 includes a plurality of tunedcircuits 30 a-30 n that are operably coupled to the antennas 16 a-16 n.The tuned circuits 30 a-30 n are configured to receive RF signal(s) fromthe wireless device 14 within a predetermined RF frequency range. Thetuned circuits 30 a-30 n discard RF signals that are not within thepredetermined RF range. A plurality of RF amplifiers 32 a-32 n areoperably coupled to the tuned circuits 30 a-30 n. The RF amplifiers 32a-32 n are configured to increase the gain of the RF bursts present onthe RF signal. A plurality of detectors (or comparators) 34 a-34 n areoperably coupled to the RF amplifiers 32 a-32 n to detect the leadingedge of each RF signal.

A plurality of counters 36 a-36 n are operably coupled to the detectors34 a-34 n. Each counter 36 a-36 n is configured to start counting andgenerate a count value (e.g., COUNT_A-COUNT_N) in response to receivinga signal START_A-START_N from a corresponding detector 34 a-34 n. Amicroprocessor 40 is operably coupled to the counters 36 a-36 n forreceiving the count values COUNT_A-COUNT_N generated by the counters 36a-36 n. The microprocessor 40 stores the count values COUNT_A-COUNT_Nfor the counter 36 a-36 n and makes a determination of the location ofthe wireless device 14 in response to processing the count valuesCOUNT_A-COUNT_N. Rapid logic 42 is operably coupled to the detectors 34a-34 n, the counters 36 a-36 n, and the microprocessor 40. The rapidlogic 42 is generally defined as customized digital circuitry that isconfigured to control the counters 36 a-36 n and/or the detectors 34a-34 n under both time-critical and non-time-critical situations.

The rapid logic 42 is configured to enable or reset the detectors 34a-34 n in response to receiving a signal READY from the microcontroller40. The rapid logic 42 transmits a signal ARM to the detectors 34 a-34 nin response to receiving the signal READY. Each counter 36 a-36 n isconfigured to initiate counting in response to the signalSTART_A-START_N from the corresponding detector 34 a-34 n. The counters36 a-36 n are configured to stop counting in response to a signal LATCHtransmitted from the rapid logic 42. The rapid logic 42 transmits asignal READ to the microcontroller 40 to control the microcontroller 40to read the count values for each counter 36 a-36 n. The counters 36a-36 n receive a signal RESET from the rapid logic 42 to clear thecontents of the counters 36 a-36 n to zero and to initiate a new countsequence in response to receiving RF bursts on a new RF signal. Thecounters 36 a-36 n transmit a signal OVERFLOW to the rapid logic 42 tonotify the rapid logic 42 of an overflow condition at one or more of thecounters 36 a-36 n.

In operation, the rapid logic 42 may transmit the signal ARMsimultaneously to the detectors 34 a-34 n such that the detectors 34a-34 n are armed to enable detection of the RF signal. Each counter 36a-36 n starts a count sequence in response to a corresponding detector34 a-34 n detecting the presence of an RF burst on the RF signal. Eachcounter 36 a-36 n may be arranged such that each counter 36 a-36 n iscapable of achieving an overflow condition. In general, the firstcounter 36 a-36 n that reaches an overflow condition is generallyindicative of the channel (e.g., CHAN_A-CHAN_N) (or antenna 16 a-16 n)that receives the RF signal first. When a counter 36 a-36 n overflows,such a counter 36 a-36 n transmits the signal OVERFLOW to the rapidlogic 42.

The rapid logic 42 transmits the signal LATCH to the remaining counters36 a-36 n that may be in the process of counting (or within a countsequence) to stop counting or to cease the count sequence in response tothe first counter 36 a-36 n reaching the overflow condition. As notedabove, it may be assumed that the first antenna (or channel) to receivethe RF signal may include the first counter 36 a-36 n to experience anoverflow condition. The count (or count values COUNT_A-COUNT_N) of thecounters 36 a-36 n that did not experience the overflow condition obtainlesser count totals than the counter that experiences the overflowcondition. The size of the count is generally indicative of the order inwhich the antennas received the RF signal. As such, the counter with thesmallest count may be determined as the antenna 16 a-16 n which was thelast to detect the RF signal. The counts for each counter 36 a-36 n isgenerally proportional to the delay time between RF signal detectionbetween the antennas 16 a-16 n. The maximum delay time that may beexhibited is generally between the antennas 16 a-16 n that arediagonally positioned to one another. For example, in reference to FIG.1, assuming that antenna 16 b is the first to detect the RF signal, thedelay time between antenna 16 b and 16 n may be considered to be themaximum delay time as antenna 16 a and/or antenna 16 c are likelycandidates to detect the RF signal next, before antenna 16 n.

Each counter 36 a-36 n may have sufficient capacity to allow the lastcounter 36 a-36 n to begin counting (or begin a count sequence) beforethe first counter 36 a-36 n reaches an overflow condition. Once theoverflow condition has occurred, the rapid logic 42 transmits the signalREAD so that the microcontroller 40 reads the count valuesCOUNT_A-COUNT_N from the counters 36 a-36 n. The rapid logic 42transmits the signal RESET to the counter 36 a-36 n to clear thecounters 36 a-36 n in response to receiving the signal READY from themicroprocessor 40. The microcontroller 40 determines the location of thewireless device 14 based on the count values stored therein and reportsthe location of the wireless device 14 on the location signal which issent to the body controller 20 via the data bus. The body controller 20may use the data on the location signal to perform one or more of thevehicle operations described above. The rapid logic 42 transmits thesignal ARM to the detectors 34 a-34 n to initiate the detection processagain.

It is generally contemplated that the counters 36 a-36 n may countcycles of the RF signal or alternatively, the counters 36 a-36 n maycount pulses of a common clock reference. In one example, the counters36 a-36 n may be implemented as high-speed counters. In yet anotherexample, the counters 36 a-36 n may be implemented as analog timeinterval integrators where an A/D converter may be needed.

Referring now to FIG. 3, diagrams corresponding to RF bursts of the RFsignal and binary signals are shown at 50 and 60, respectively. At 50,the RF bursts on the RF signal are shown in a raw format. At 60, RFbinary equivalents of the RF bursts are shown. In general, the centralcontroller 18 is configured to detect the leading edges of the RFbursts. In one example, the wireless device 14 may be configured totransmit a plurality of RF bursts or signals in response to the wirelessdevice 14 being actuated by the vehicle occupant. Data may be encoded onthe RF signal by shifting the repetition rate.

While a single transmitted burst is sufficient to detect the location ofthe wireless device 14, a single burst on the RF signal may not containany of the information relevant to the particular vehicle operation thatis to be performed. Firstly, data may be needed to distinguish onewireless device 14 from another. For example, whether the wirelessdevice 14 is a keyfob or a TPMS sensor or whether the wireless device 14belongs to the vehicle 12 or another vehicle. Secondly, data may beneeded to provide a command or a measurement, such as LOCK or UNLOCK forRKE operation, or TIRE PRESSURE and TEMPERATURE for TPMS operation.

One way to carry such data on the RF signal is to repeat these short RFbursts with some pattern. The repetition rate is generally the measureof how rapidly the bursts are repeated (as in “bursts per second”).Alternatively, this could be expressed as the time between bursts.

A constant repetition rate may carry minimal amounts of information, sothe rate is varied by some scheme. For example, a delay between burstsof 2 milliseconds may represent a binary 0 and a delay of 3 millisecondsmay represent a binary 1.

An upper limit of the repetition rate is dependent on the time it takesthe RF signal in flight to cover the distance between diagonally opposedantennas 16 a-16 n. In general, it may not be optimal for a new burst toarrive before the previous burst had traversed all antennas 16 a-16 n.The repetition rate may be slower than that since the completeprocessing cycle may be needed to be complete, the slowest part of whichmay be the sequential reading of the counters 36 a-36 n by themicroprocessor 40.

In reference to 60, the RF signal received on CHAN_A (or at antenna 16a) is the first detected RF signal to arrive at the antenna array 16.The second detected RF signal to arrive at the antenna array 16 is onCHAN_B. The third detected RF signal to arrive at the antenna array 16is on CHAN_N. In lieu of the sequence of the detected RF signals at thecorresponding antennas (16 a, 16 b, and 16 n), the central controller 18may infer that the direction of the RF signal came from a wirelessdevice 14 positioned proximate to the front passenger side of thevehicle 12 or at the passenger-front door side of the vehicle 12.

Referring back to FIG. 2, it is generally contemplated the centralcontroller 18 may include a surface acoustic wave (SAW) device alongwith each tuned circuit 30 a-30 n and RF amp 32 a-32 n. For example, thecentral controller 18 may include the tuned circuit 30 a, the RF amp 32a and a SAW filter (not shown) operably coupled with one another to forma headend circuit. The headend circuit may be operably coupled to theantenna 16 a to receive the RF signal. The tuned circuits 30 b-30 n andthe RF amp 32 b-32 n may also be coupled to respective SAW filters toform additional headend circuits for each antenna 16 b-16 n. The outputof each headend circuit may be fed to each corresponding detector 34a-34 n for RF signal detection.

FIG. 4 generally illustrates a single RF chirp burst signal 70 that ispresented to an input of the headend circuit. Each headend circuit maygenerate an impulse signal 80 that is fed to a corresponding detector 34a-34 n. In general, the SAW filter may generate the impulse signal 80 inresponse to the RF chirp burst signal 70. Each corresponding detector 34a-34 n may detect the peak (or a predetermined level) of thecorresponding impulse signal 80 to detect the presence of the RF signalon each of the channels CHAN-A-CHAN_N. The impulse signal 80 may providebetter noise rejection characteristics than that of the RF burst signal70. The operation of the counters 36 a-36 n, the microcontroller 40, andthe rapid logic 42 remains the same as noted in connection with FIG. 2in the event the headend circuits are implemented.

A chirped RF burst, as received by a suitable chirp filter (such as achirp SAW of the correct tuning) provides a distinctive signal and mayinclude better noise rejection than a constant-frequency RF burst. Inaddition, a chirp SAW filter (also known as a convolution filter) mayinclude the effect of “sharpening” the burst of RF energy into a brieferduration waveform with a higher peak amplitude. Such a sharpeningimproves the time accuracy of detection.

Referring now to FIG. 5, a zone map 90 is shown for determining thelocation of the wireless device 14 in accordance to one embodiment ofthe present invention. The antennas 16 a-16 n of the antenna array 16may be superimposed over the zone map 90 for purposes of describing themanner in which the central controller 18 determines the location of thewireless device 14. In general, each zone 1-8 within the zone map 90 maycorrespond to a predesignated section of the vehicle 12 and an areaextending away from each predesignated section of the vehicle 12. Forexample, zone 1 may correspond to a passenger-front door side of thevehicle and the area extending away from the passenger-front door sideof the vehicle, zone 2 may correspond to a front-passenger side of thevehicle and the area extending away from the front-passenger side of thevehicle, zone 3 may correspond to a front driver side of the vehicle andthe area extending away from the front driver side of the vehicle, zone4 may correspond to a driver-front door side of the vehicle and the areaextending away from the driver-front door side of the vehicle, zone 5may correspond to a driver-rear door side of the vehicle and the areaextending away from the driver-rear door side of the vehicle, zone 6 maycorrespond to a rear-driver side of the vehicle and the area extendingaway from the rear-driver side of the vehicle, zone 7 may correspond toa rear-passenger side of the vehicle and the area extending away fromthe rear-passenger side of the vehicle, and zone 8 may correspond to apassenger-rear door side of the vehicle and the area extending away fromthe passenger-rear door side of the vehicle.

The zone map 90 may be used in connection with Tables 1a and 1b asillustrated in connection with FIGS. 6A and 6B.

As shown in Table 1a, in the event the central controller 18 determinesthat the antenna 16 a is the first to receive the RF signal, the antenna16 b is second to receive the RF signal, and the antenna 16 n is thethird to receive the RF signal, the central controller 18 may determinethat the wireless device 14 is located in zone 2 (e.g., at the frontpassenger side of the vehicle, or area extending therefrom). In theevent the central controller 18 determines that the antenna 16 a is thefirst to receive the RF signal, the antenna 16 n is second to receivethe RF signal, and antenna 16 b is third to receive the RF signal, thecentral controller 18 may determine that the wireless device 14 islocated in zone 1 (e.g., at the passenger front door side of the vehicleor area extending therefrom).

In the event the central controller 18 determines that the antenna 16 bis first to receive the RF signal, the antenna 16 a is second to receivethe RF signal, and antenna 16 c is the third to receive the RF signal,the central controller 18 may determine that the wireless device 14 islocated in zone 3 (e.g., at the front-driver side of the vehicle areaextending therefrom). In the event the central controller 18 determinesthat the antenna 16 b is the first to receive the RF signal, the antenna16 c is second to receive the RF signal, and the antenna 16 a is thethird to receive the RF signal, the central controller 18 may determinethat the wireless device 14 is located in zone 4 (e.g., at thedriver-front door side of the vehicle or area extending therefrom).

Similarly, the corresponding zone (e.g., the location of the wirelessdevice 14 with respect to the vehicle) may be determined in the eventthe central controller 18 determines that antenna 16 c is the first toreceive the RF signal or in the event the central controller 18determines that antenna 16 n is the first to receive the RF signal inthe manner shown in Table 1b. As illustrated by Tables 1a-1b, by rankingthe order in which the RF signal is received on each antenna 16 a-16 n,it is possible to determine which zone 1-8 the wireless device 14 ispositioned in. It is generally contemplated that the central controller18 (or other suitable controller) may include an algorithm storedtherein containing instructions for determining the corresponding zonein which the wireless driver 14 is positioned in accordance to themanner described above. For example, such an algorithm may take intoaccount the particular sequence as to when an RF signal is detected tohave arrived at the antennas 16 a-16 n and to determine the particularlocation of the wireless device 14 with respect to a particular zone.

Zone map 90 and Tables 1a and 1b are generally used by the centralcontroller 18 to determine a first level of location. Such a first levelof location provides information as to which zone the wireless device 14is positioned within. In the event it is desired to obtain moreinformation related to the location of the wireless device 14 within aparticular zone, a hyperbolic grid may be constructed to determine theposition of the wireless device 14 within a particular zone. Thehyperbolic grid is generally used to provide for a second level oflocation. The hyperbolic grid may be defined by hyperbolic curves thatform grid cells. The grid cells of the hyperbolic grid may be assignedto various delay times between the detected RF signal at the antennas 16a-16 n. The delay time between detected RF signals at the antennas 16a-16 n generally correspond to the difference between count valuesdetermined by the central controller 18 as discussed in connection withFIG. 2.

Referring now to FIG. 7, a hyperbolic grid 100 in accordance to oneembodiment of the present invention is shown. In general, the hyperbolicgrid 100 corresponds to zones 1-2 as shown in connection with FIG. 5. Itis generally contemplated that an entire grid may be constructed toinclude all zones as shown in connection with FIG. 5. The grid 100 isdefined by a number of grid cells positioned within zone 1-2. Asdepicted in grid 100, the location of antenna 16 a is indicated at “A”.The x-axis of the grid 100 generally corresponds to the difference incounts between the count value stored in counter 36 c (e.g., COUNT_C)and the count value stored in counter 36 n (e.g., COUNT_N). The y-axisof the grid 100 corresponds to the difference in counts between thecount value stored in counter 36 c (e.g., COUNT_C) and the count valuestored in counter 36 b (e.g., COUNT_B).

In general, the antenna that first detects the RF signal and/or theantenna that is next to detect the RF signal provides information as tothe particular zone in which the wireless device 14 is located (seeTable 1a and 1b in FIGS. 6A and 6B, respectively). The difference incounts between the counts of the second and/or third antennas and thelast antenna to detect the RF signal provides information as to theparticular grid cell in which the wireless device 14 is located.

The values for the cells generally start at (0,0) and extend to (9,0) onthe x-axis, and (0,9) on the y-axis. The value of 9 generally representsthe maximum count difference between the count values. The maximum countdifference may be greater than or less than 9. The particular maximumcount difference may vary based on the desired criteria of a particularimplementation. The ordered number pairs for each cell are,respectively, the count values stored in counter 36 n (e.g., COUNT_N)minus the count value stored in counter 36 c (e.g., COUNT_C) and thecount value stored in counter 36 b (e.g., COUNT_B) minus the count valuestored in counter 36 c (e.g., COUNT_C). In other words, each cell inzones 1 and 2 of the grid 100 is defined by the following equation:(COUNT_N−COUNT_C,COUNT_B−COUNT_C)  EQ: 1

Each cell in zones 3 and 4 is defined by the following equation:(COUNT_C−COUNT_N,COUNT_A−COUNT_N)  EQ: 2

Each cell in zones 5 and 6 is defined by the following equation:(COUNT_N−COUNT_A,COUNT_B−COUNT_A)  EQ: 3

Each cell in zones 7 and 8 is defined by the following equation:(COUNT_C−COUNT_B,COUNT_A−COUNT_B)  EQ: 4

Again, cells corresponding to zones 3-8 are not shown in the grid 100.Grid 100 is shown for illustrative purposes.

Referring now to FIG. 7, a method 200 for determining the location ofthe wireless device 14 with respect to the vehicle 12 is shown. Thecentral controller 18 (or other suitable controller) includes logic(software or hardware or combination thereof) for determining thelocation of the wireless device 14 with respect to the vehicle 12 asdescribed in the following blocks. Such blocks as described below may beperformed sequentially or non-sequentially. Further such blocks arecapable of being performed simultaneously or serially with respect toone another. The particular order and execution times for the blocks mayvary based on the desired criteria of a particular implementation.

In block 202, the central controller 18 determines which of the antennas16 a-16 n is the first to receive the RF signal. The central controller18 then determines which of the antennas 16 a-16 n is the second, thirdand fourth to receive the RF signal.

In block 204, the central controller 18 determines the particular zonein which the wireless device 14 is located based on which antenna 16a-16 n is the first to receive the RF signal and which antenna 16 a-16 nis then second and third to receive the RF signal (see FIG. 5 and Table1a and 1b in FIGS. 6A and 6B). The operation performed in block 204provides for a first level determination as to which zone the wirelessdevice 14 is located in.

In block 206, the central controller 18 generates count valuesCOUNT_A-COUNT_N in response to receiving the RF signal at the antennas16 a-16 n.

In block 208, the central controller 18 inserts at least three countvalues COUNT_A-COUNT_N into one or more of the EQs. 1-4 to determine thelocation of the wireless device within a particular zone with respect tothe vehicle 12. The particular equation used may vary based on whichparticular zone from the zone map 90 is determined to include thewireless device 14.

In general, the central controller 18 determines the zone (e.g. 1-8) inwhich the wireless device 14 is located based on the arrival time of theRF signal at the antennas 16 a-16 n. The central controller 18 furthergenerates count values based on the arrival time of the RF signal at theantennas 16 a-16 n. The central controller 18 determines the particularlocation of the wireless device 14 within the zone with respect to thevehicle 12 by inserting the various count values into Eqs. 1-4. Thecentral controller 18 transmits the location signal which is indicativeof the location of the wireless device 14 to the body controller 20 sothat the body controller 20 controls a particular vehicle operationbased on the location signal. It is contemplated that any suitablemodule/controller may be employed other than the central controller 18within the vehicle 12 to determine the location of the wireless device14 within a particular zone.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

1. An apparatus for determining a location of a wireless device withrespect to a vehicle, the apparatus comprising: a plurality of antennasfor being positioned about the vehicle to receive a wireless signal fromthe wireless device and each antenna of the plurality of antennas isarranged to be positioned in a zone about the vehicle in which thewireless device is capable of being positioned within, the wirelessdevice for being one of carried by a user and positioned on the vehicle,and the wireless signal being indicative of a predetermined vehicleoperation; and a controller for being operably coupled to each antennaand being configured to: determine the zone which includes the portablewireless device based on an order in which the plurality of antennasreceives the wireless signal; generate a location signal indicative ofthe location of the wireless device based on the order in which theplurality of antennas receives the wireless signal; and perform thepredetermined vehicle operation based on the location signal.
 2. Theapparatus of claim 1 wherein the wireless device comprises one of a keyfob, a tire pressure monitor sensor, a switch, and an occupant sensor.3. The apparatus of claim 1 wherein the predetermined vehicle operationcorresponds to one of a remote keyless entry (RKE), carfinder, passiveentry passive start, immobilizer, tire pressure monitoring, andoccupancy detection.
 4. The apparatus of claim 1 wherein the controlleris further configured to generate a count value for each wireless signalreceived at the plurality of antennas, wherein the count valuescorrespond to the order in which each antenna of the plurality ofantennas receives the wireless signal.
 5. The apparatus of claim 4wherein the controller is further configured to determine a differencebetween the count values to determine the location of the wirelessdevice in the zone of the vehicle.
 6. The apparatus of claim 4 whereinthe count values comprise a first count value and a second count value,the first count value being greater than the second count value, thefirst count value being indicative of a first antenna that is first toreceive the wireless signal and the second count value being indicativeof a second antenna that is second to receive the wireless signal. 7.The apparatus of claim 1 further comprising: a tuned circuit forreceiving the wireless signal at a predetermined frequency from aparticular antenna of the plurality of antennas; an amplifier forincreasing the gain of the wireless signal after receiving the wirelesssignal at the predetermined frequency; a detector for detecting thewireless signal after the amplifier increases the gain of the wirelesssignal; and a counter for generating a count value after the detectordetects the wireless signal.
 8. The apparatus of claim 1 wherein eachantenna of the plurality of antennas are equally spaced apart from oneanother.
 9. An apparatus for determining a location of a wireless devicewith respect to a vehicle, the apparatus comprising: a controller forbeing operably coupled to a plurality of antennas positioned about thevehicle for receiving a wireless signal from the wireless device andeach antenna of the plurality of antennas is arranged to be positionedin a zone about the vehicle in which the wireless device is capable ofbeing positioned within, the wireless device for being one of carried bya user and positioned on the vehicle, and the wireless signal beingindicative of a predetermined vehicle operation, the controller beingconfigured to: determine the zone which includes the portable wirelessdevice based on an order in which the plurality of antennas receives thewireless signal; generate a location signal indicative of the locationof the wireless device based on the order in which the plurality ofantennas receives the wireless signal; and perform the predeterminedvehicle operation based on the location signal.
 10. The apparatus ofclaim 9 wherein the wireless device comprises one of a key fob, a tirepressure monitor sensor, a switch, and an occupant sensor.
 11. Theapparatus of claim 9 wherein the predetermined vehicle operationcorresponds to one of a remote keyless entry (RKE), carfinder, passiveentry passive start, immobilizer, tire pressure monitoring, andoccupancy detection.
 12. The apparatus of claim 9 wherein the controlleris further configured to generate a count value for each wireless signalreceived at the plurality of antennas, wherein the count valuescorrespond to the order in which each antenna of the plurality ofantennas receives the wireless signal.
 13. The apparatus of claim 12wherein the controller is further configured to determine a differencebetween the count values to determine the location of the wirelessdevice in the zone of the vehicle.
 14. The apparatus of claim 12 whereinthe count values comprise a first count value and a second count value,the first count value being greater than the second count value, thefirst count value being indicative of a first antenna that is first toreceive the wireless signal and the second count value being indicativeof a second antenna that is second to receive the wireless signal. 15.The apparatus of claim 9 further comprising: a tuned circuit forreceiving the wireless signal at a predetermined frequency from aparticular antenna of the plurality of antennas; an amplifier forincreasing the gain of the wireless signal after receiving the wirelesssignal at the predetermined frequency; a detector for detecting thewireless signal after the amplifier increases the gain of the wirelesssignal; and a counter for generating a count value after the detectordetects the wireless signal.
 16. A vehicle apparatus comprising: aplurality of antennas for being positioned about the vehicle to receivea wireless signal from the wireless device and each antenna of theplurality of antennas is arranged to be positioned in a zone about thevehicle in which the wireless device is capable of being positionedwithin, the wireless device for being one of carried by a user andpositioned on the vehicle, and the wireless signal being indicative of apredetermined vehicle operation; and each antenna of the plurality ofantennas for being operably coupled to a controller that determines thezone which includes the portable wireless device based on an order inwhich the plurality of antennas receives the wireless signal, generatesa location signal indicative of the location of the wireless devicebased on the order in which the plurality of antennas receives thewireless signal, and performs the predetermined vehicle operation basedon the location signal.
 17. The vehicle apparatus of claim 16 furthercomprising: a circuit for receiving the wireless signal at apredetermined frequency from a particular antenna of the plurality ofantennas; an amplifier for increasing the gain of the wireless signalafter receiving the wireless signal at the predetermined frequency; adetector for detecting the wireless signal after the amplifier increasesthe gain of the wireless signal; and a counter for generating a countvalue after the detector detects the wireless signal.